I’ve created a project to run Klaus Dormann’s functional tests in my VS Code db65xx debugging extension. Three test builds are available, one for the 6502, one for the 65C02 extended functions, and one testing the decimal mode. Here are some screenshots.
Note that the 6502 and decimal mode tests can also be run on the 65816 core by changing the cpu launch argument in the launch.json file. The 65C02 extended tests can’t be run successfully on the 65816 core of course, becuase the processor uses many of those opcodes for other instructions and address modes.